In Ref. [1]} the authors reported the observation of a compact binary coalescence involving a \(22.2-24.3\ M_{\odot }\)  black hole and a compact object with a mass of a \(2.50-2.67 \ M_{\odot }\)  (all measurements quoted at the \( 90 \%\)  credible level). The announcement of the GW190814 event [1]} triggered various theoretical studies concerning the equation of state (EoS) of dense nuclear matter, in order to explain the possibility of the second partner to be a very massive neutron star. It is worth pointing out that the authors in Ref. [1]} did not exclude the possibility that the second partner to be a neutron star or an exotic compact object, i.e. quark star, boson star or gravastar. The consideration of a neutron star as the second partner has been studied in recent Refs. [4]}, [5]}, [6]}, [7]}, [8]}, [9]}, [10]}, [11]}, [12]}, [13]}, [14]}, [15]}, [16]}. On the other hand, the case that the second partner is a quark or hybrid star has been explored in Refs. [17]}, [18]}, [19]}, [20]}, [21]}. Finally, some modified theories of gravity have also been applied as possible solutions to the problem [22]}, [23]}, [24]}.
